Urinary tract infection (UTI) is the most common hospital acquired infection and is usually associated with the use of an indwelling catheter. Bacteria colonize the bladder and form a slimy coat on the catheter called a biofilm. Bacteria in a biofilm are able to evade host defense mechanisms and also become less susceptible to antibiotic therapy. As a consequence, catheter associated UTI is more difficult to eradicate. The long-term goal of this project is to find new ways to interfere with bacterial biofilm formation so that treatment of catheter associated UTI is more effective. Most previous genetic studies of Escherichia coli bacteria in biofilms have focused on biofilms composed of only one type of bacteria. These 1-species biofilms usually contained the laboratory strain E. coli K-12. However biofilms in nature are typically composed of a consortium of organisms. The bacteria within the biofilm community may communicate among themselves. For example, they may share, or compete for, metabolic products or they may respond to extracellular signals. The outcome of these microbial interactions may be symbiotic or competitive. Certainly the microenvironment of a multi-species biofilm is different from a mono-culture biofilm that contains only E. coli K-12. [unreadable] [unreadable] We propose to study the gene expression of a clinical E. coli that is growing in a biofilm together with Enterococcus faecalis. Each of these bacterial species is a common cause of catheter associated UTI. A genomic approach will be used to discover genes that are key to formation of 2-species biofilms. High throughput genetic methods will be used to identify E. coli genes that are differentially expressed in a 2-species biofilm and genes that are uniquely required for formation of 2-species biofilms. Future studies will identify the mechanism of action of each of the genes discovered. Results of the proposed experiments may illuminate new targets for intervention therapies that disrupt biofilm formation. This may lead to more effective treatment of catheter-associated infections. [unreadable] [unreadable]